Method for handling tubulars and rigidizer therefor

ABSTRACT

A rigidizer and method for its use in supporting a tubular string during handling operations. The rigidizer includes upper and lower sleeves which pivotally open and close to clamp about the string. The upper and lower sleeves are rigidly connected by a number of structural telescopic legs that allow adjustment to different lengths for accommodating different strings. The rigidizer is installed on the string when the string is in a horizontal position and provides structural support to thin-walled components during upending and handling. Once the string is vertically oriented, the rigidizer is removed prior to being run into a marine riser or well.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a non-provisional application of co-pending U.S. Provisional Application No. 61/904,915 filed on Nov. 15, 2013, the benefit of which is claimed and which incorporated herein in its entirety.

BACKGROUND

1. Field of the Invention

This invention relates generally to drilling equipment used in the hydrocarbon production industry, and specifically to a rigidizer and a method for handling tubulars during offshore drilling and/or production operations.

2. Background Art

In the hydrocarbon production industry, tubular goods, including drill strings, casings and tubing, referred to simply as tubulars, must at varying stages be run, i.e. lowered, into or raised from a well. An elevator is a device that is carried by the drilling rig's traveling block or a top drive, which supports the tubular for the purpose of raising or lowering it. An elevator may clamp along the side of a tubular using slips and dies to exert a radial clamping force on the tabular wall, or an elevator may use a bushing to support the tubular at the lower lip of a box connector.

A drill string, well casing, riser, or production string is made of many stands of connected lengths of tubulars and/or subs. The stands or individual lengths of tubulars and subs are assembled, typically by threading, as they are being run. Individual lengths of tubulars or stands are usually staged near the drilling rig for running operations. Although in some platforms tubulars are stored vertically, in many cases they are stored horizontally, in which case they must be upended for running.

For must tubulars, upending from a horizontal orientation to vertical is not problematic. However, for some thin-walled string components, the imposed bending forces during the upending process can plastically deform the component, resulting in ovalization or folding,

FIG. 1 illustrates one such component. FIG. 1 is an axial cross section of a subsea lower landing string 10, which is run into a blowout preventer (not illustrated). Subsea lower landing string 10 may include a landing string pup joint and crossover 12, a ported slick joint 14, one or more spacer spools 16, a retainer valve 18, a shear sub 20, a subsea safety tree with integral slick joint 22, and a tubing hanger running tool adapter 24. Retainer valve 18 and subsea safety tree 22 are typically heavy components, which sandwich shear sub 20. Shear sub 20 is a thin walled component designed so that it may be readily severed by the shears and rams of the blowout preventer (not illustrated) in case of an emergent well casualty. Accordingly, when upending subsea lower landing string 10 in preparation for running, shear sub 20 is prone to bending damage.

SUMMARY OF THE INVENTION

As described herein, an exemplary embodiment of a rigidizer includes upper and lower sleeves which directly clamp about components in a landing string. The upper and lower sleeves are rigidly connected by a number of structural legs, which may take the form of cylindrical tubular members. The rigidizer provides additional mechanical strength and stiffness to protect thin-walled tubing components in a landing string during handling operations.

The rigidizer is preferably adjustable to different lengths so that strings having shear subs of different lengths can be protected using a single rigidizer. More specifically, each structural leg may be telescopic, including an inner tubular member nested and slideably disposed within an outer tubular member. Inner tubular members may be positioned with respect to outer tubular members and held in place using a locking system once the desired extension or retraction of the legs have been achieved, as described in greater detail.

The upper and lower sleeves are axially split into two semi-circular portions joined together at one edge by a hinge mechanism to allow relative pivotal movement of the respective portions. Such an arrangement allows the rigidizer to be rapidly installed on and removed from the string. The opposing edges of the semi-circular portions of the upper and lower sleeves are removably joined by a latching mechanism.

According to a preferred method, the rigidizer is installed on the string to be protected when the string is in a horizontal position. The axial length of the rigidizer is adjusted if necessary so that the upper and tower sleeves align with the string components that they clamp about. The rigidizer is opened by unlatching the latching mechanisms and pivoting the rigidizer to the open position at the hinge mechanisms. The rigidizer is then positioned in place around the string, pivoted to the closed position at the hinge mechanisms, and latched, thereby clamping rigidizer in place. The string is then upended and transferred to the drilling rig for running. Once the string is vertically oriented, the rigidizer is removed prior to being run into a marine riser or well.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail hereinafter on the basis of embodiments represented un the accompanying figures, in which:

FIG. 1 is an axial cross section of a typical subsea lower landing string of prior art, showing a thin-walled shear sub sandwiched between two heavy components;

FIG. 2A is an elevation view of a portion of the subsea lower landing string of FIG. 1 equipped with a rigidizer clamped about the shear sub according to a preferred embodiment of the invention;

FIG. 2B is an elevation view of a portion of a subsea lower landing string having a longer shear sub than the subsea lower landing string of FIG. 2A, shown with the rigidizer of FIG. 2A in an axially extended configuration clamped about the shear sub according to a preferred embodiment of the invention;

FIG. 3A is a plan view of the top end of the rigidizer of FIG. 2A, showing an upper sleeve with four legs radially disposed about the upper sleeve;

FIG. 3B is an elevation view of the left side of the rigidizer of FIG. 3A, showing the upper sleeve connected to a lower sleeve with telescopic legs;

FIG. 3C is an elevation view of the front of the rigidizer of FIG. 3A, showing hinge mechanisms at the upper and lower sleeves;

FIG. 3D is a plan view of the bottom end of the rigidizer of FIG. 3A, showing the lower sleeve and the four legs radially disposed about the lower sleeve;

FIG. 4 is an axial cross section of a telescopic leg of the rigidizer of FIG. 3A taken along line 4-4 of FIG. 3A, showing an inner tubular member slideably disposed within an outer tubular member and a locking system for fixing the relative position between the two tubular members;

FIG. 5A is a perspective view of the back of the rigidizer of FIG. 2A in a vertical orientation and an open state, showing latching mechanisms at the upper and lower sleeves;

FIG. 5B is a perspective view of the front of the rigidizer of FIG. 5A;

FIG. 6 is a perspective view of the left side and top end of the rigidizer of FIG. 2A in a horizontal orientation and a closed state; and

FIG. 7 is an enlarged perspective view of a portion of the rigidizer of FIG. 5A, showing details of the locking system.

DETAILED DESCRIPTION OF THE INVENTION

In the interest of clarity, not all features of an actual implementation or method are described in this specification. Also, the “exemplary” embodiments described herein refer to examples of the present invention. In the development of any such actual embodiment, numerous implementation-specific decisions may be made to achieve specific goals, which may vary from one implementation to another. Such would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. Further aspects and advantages of the various embodiments and related methods of the invention will become apparent from consideration of the following description and drawings.

The foregoing disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” “uphole,” “downhole,” “upstream,” “downstream,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the apparatus in use or operation in addition to the orientation depicted in the figures,

FIG. 2A illustrates a portion of subsea lower landing string 10. A rigidizer 100 is clamped about shear sub 20 according to a preferred embodiment of the invention. Rigidizer includes an upper sleeve 114, which directly clamps about retainer valve 18, and a lower sleeve 116, which directly clamps about subsea safety tree 22. Upper sleeve 114 is rigidly connected to lower sleeve 116 by a number of structural legs 112, which in one or more embodiments take the form of cylindrical tubular members. However, other types of structural members may be used in place of cylindrical tubes for legs 112 as appropriate. Rigidizer 100 provides additional mechanical strength and stiffness to subsea lower landing string 10 during handling operations, particular upending or laying down string 20, to prevent bending damage the thin-walled shear sub 20.

According to a preferred embodiment, rigidizer 100 is readily adjustable to different lengths so that strings having shear subs 20 of different lengths can be protected using a single rigidizer 100. For example, FIG. 2B illustrates a portion of subsea lower landing string 10′, which is substantially similar to subsea lower landing string 10 of FIG. 2A except that its shear sub 20′ is longer than shear sub 20 of FIG. 2A. Structural legs 112 are telescopic, thereby allowing axial adjustment.

More specifically, each telescoping leg 112 includes an inner tubular member 128 nested and slideably disposed within an outer tubular member 130. In the illustrated embodiment, each inner tubular member 128 is structurally attached to upper sleeve 114, and each outer tubular member 130 is structurally attached to sleeve 116. Structural attachment may be by bolting or welding, for example.

Telescoping of legs 112 may be by any known manner. In a preferred embodiment, inner tubular members 128 are manually positioned with respect to outer tubular members 130 and are held in place using a locking system 138 once the desired extension or retraction of the leg 112 has been achieved, as described in greater detail. In an alternative embodiment (not illustrated), legs 112 are formed of piston-cylinder arrangement, and axial length is hydraulically or pneumatically controlled.

FIGS. 3A-3D are top plan, left elevation, front elevation, and bottom plan views of rigidizer 100, respectively, shown in a closed position. FIGS. 5A and 5B are perspective views of the back and front of rigidizer 100, respectively, shown in an open position. FIG. 6 is a perspective view of the left side of rigidizer shown in a closed position and in a horizontal orientation.

Referring collectively to FIGS. 3A-3D and 5A, 5B, and 6, each sleeve 114, 116 is split into two portions along seams 115. Sleeve 114 is split into portions 114 a and 114 b, and sleeve 116 is split into portions 116 a and 116 b. Although not a limitation, in certain embodiments, the portions can substantially similar in dimensions. Each sleeve defines an outer surface 120 and preferably includes inner lining 118, which may be formed of an elastomeric or polymeric material for example. Each sleeve includes a hinge mechanism 122, which may be disposed adjacent the outer surface 120 along one seam 115 to allow relative pivotal movement of the respective portions. Such an arrangement allows rigidizer 100 to be rapidly installed on and removed from string 20 (FIG. 2A).

Each sleeve may further include a latching mechanism 124 adjacent the seam 115 opposite the hinged seam to allow the first and second portions of a sleeve to be secured to one another so as to form a complete cylinder. In a preferred embodiment, latching mechanism 124 includes swing-style clamping bolts secured with nuts and cotter pins. However, other suitable latching mechanisms may be used. Persons of skill in the art will appreciate that latching mechanism 124 can be activated in any manner known in the art, which can include mechanical activation, hydraulic activation, electrical activation or manual activation.

In certain embodiments, rigidizer 100 includes at least two legs 112. In other embodiments, rigidizer 100 may include three, four or more telescoping legs. The number of telescoping legs will depend in part on the outer circumferential size of sleeves 114, 116. Each telescoping leg extends between sleeves 114 and 116 so as to be substantially parallel with the axis of string 20 (FIG. 2A) when clamped therein. Preferably, legs 112 are symmetrically spaced about the outer perimeter of sleeves 114, 116.

Each telescoping leg 112 may be mounted to its respective sleeves 114, 116, preferably adjacent the outer surface 120 of the sleeve, so as to be radially spaced apart from the sleeve, thereby allowing greater relative movement and clearance between sleeve portions when rigidizer 100 is being removed or installed. Thus, in certain embodiments, one or more telescoping legs may be secured to a sleeve with a spacer mechanism 142. Rigidizer 100 is designed so that it can be installed or removed when the string is in the vertical or horizontal position.

As best seen in FIGS. 3A and 3D, in the embodiment illustrated, upper sleeve 114 has a smaller inner diameter 214 than the inner diameter 216 of lower sleeve 116. The required upper and lower inner diameters 214, 216 are determined by the size of retainer valve 18 and subsea safety tree 22 (FIG. 2A) or other string components about which upper and lower sleeves 114, 116 clamp.

Each sleeve 114, 116 may also include an inner diameter adjustment mechanism 125 (FIG. 5A) that allows at least a portion of the inner circumference of the sleeve to be adjusted to accommodate drill string components of different diameters. Adjustment mechanism 125 may take the form of removable plates, such as shown, or adjustable extensions, such as screws, radially extending inward and disposed on along the inner surface 118 of the sleeves.

FIG. 4 is an axial cross section of a structural leg 112. FIG. 7 is an enlarged detail of a portion of FIG. 5A. Locking system 138 is best understood with reference to FIGS. 2B and 4-7. In the illustrated embodiment, locking system 138 for each leg 112 is a removable dual pin assembly that passes entirely through both outer tubular member 130 and inner tubular member 128 along a diameter thereof. Outer tubular member 130 includes a single pair of longitudinally spaced locking holes 139 formed therethrough at a predetermined inter-hole center-to-center distance. Inner tubular member 128 includes a number of pairs of longitudinally spaced locking holes 140 formed therethrough along the length of the member, each pair having an inter-hole spacing that corresponds to that of locking holes 139. The proximal ends of two pins 241 are fastened to a plate 242, such as by welding, at the predetermined inter-hole center-to-center distance. Pins 241 have a diameter so as to readily slide into and out of locking holes 139, 140 without excessive play. A handle 243 may be affixed to plate 242 for ease of operation. The distal end of each pins 241 is chamfered and has a locking hole formed therethrough so as to receive a cotter pin or locking clip 245. Once inner tubular member 128 is longitudinally adjusted to a desired position with respect to outer tubular member 130 so that a pair of locking holes 140 aligns with locking holes 140, pins 241 are inserted through the two tubular members and retained with clip 245, thereby structurally locking telescopic leg 112 at a given length.

Referring to FIG. 4, according to an embodiment, a lower bushing 180 is attached to the outer circumference of inner tubular member 128 at its lower end. Lower bushing 180 axially slides along the inner circumference of outer tubular member 130 as inner tubular member 128 slides. Similarly, an upper bushing 182 is attached to the inner circumference of outer tubular member 130 at its upper end. The outer circumference of inner tubular member 128 slides against upper bushing as inner tubular member 128 slides. Lower and upper bushings 180, 182 may be made of a thermoplastic polymeric material such as a nylon, or other suitable bearing material.

Although telescopic legs 112 are disclosed herein, legs of fixed length may be used while still maintaining the ability to adjust the axial length of rigidizer 100. In such an embodiment, the mounting position(s) of the legs 112, upper sleeve 114, and/or lower sleeve 116 may be axially adjusted.

According to a preferred method, rigidizer 100 is installed on string 20 when string 20 is in a horizontal position. The axial length of rigidizer 100 is adjusted if necessary so that upper and lower sleeves 114, 116 align with the string components that they clamp about. To do so, all pins 241 are removed from telescopic legs 112, the legs are manually extended or retracted, and pins 241 are reinstalled through locking holes 139, 140 and retained with clips 245.

Rigidizer is opened by unlatching latching mechanisms 124 and pivoting rigidizer 100 to the open position at hinge mechanisms 122. If necessary, the inner diameters 214, 216 of upper and lower sleeves 114, 116 are adjusted using inner diameter adjustment mechanism 125.

Rigidizer 100 is then positioned in place around string 20 and pivoted to the dosed position at hinge mechanisms 122. Latching mechanisms 124 are then latched, thereby clamping rigidizer in place. It not previously adjusted and if necessary, the inner diameters 214, 216 of upper and lower sleeves 114, 116 may be adjusted after installation using inner diameter adjustment mechanism 125 if such mechanism is externally accessible.

String 20 is then upended and transferred to the drilling rig for running. Once string 20 is vertically oriented, rigidizer 100 may be removed. Rigidizer 100 is removed from string 20 prior to shear sub 20 being run into a marine riser or well, simply by unfastening latching mechanisms 124, pivoting rigidizer open at hinge mechanisms 122, and removing rigidizer 100 from string 20.

The Abstract of the disclosure is solely for providing the United States Patent and Trademark Office and the public at large with a way by which to determine quickly from a cursory reading the nature and gist of technical disclosure, and it represents solely one or more embodiments.

While various embodiments have been illustrated in detail, the disclosure is not limited to the embodiments shown. Modifications and adaptations of the above embodiments may occur to those skilled in the art. Such modifications and adaptations are in the spirit and scope of the disclosure. 

What is claimed is: A1. A rigidizer for strengthening a tubular string comprising: upper and lower sleeves each having first and second semi-circular pivotally connected portions, each of said first and second semi-circular pivotally connected portions characterized by having an open configuration and a closed configuration, said upper and lower sleeves being dimensioned to clamp about said tubular string when in said closed configuration; and a first leg rigidly connected between said upper and lower sleeves so as to hold said upper and lower sleeves in coaxial alignment and separated by a first axial distance; whereby said rigidizer is operable to removably clamp about and thereby strengthen said string. A2. The rigidizer of claim A1 wherein: said first leg is selectively adjustable so as to hold upper and lower sleeves separated by a second axial distance greater than said first axial distance. A3. The rigidizer of claim A2 wherein: said first leg is telescopic, having an elongated inner tubular member slideably disposed within an elongated outer tubular member. A4. The rigidizer of claim A3 further comprising: a locking system including a pin removably disposed through apertures formed in said inner and outer tubular members. A5. The rigidizer of claim A1 further comprising: second and third legs rigidly connected between said upper and lower sleeves. A6. The rigidizer of claim A1, further comprising: an inner diameter adjustment mechanism coupled to one of the group consisting of said upper sleeve and said lower sleeve. A7. The rigidizer of claim A6, wherein: the adjustment mechanism is a radially extending extension. A8. The rigidizer of claim Al, further comprising: a latching mechanism coupled to one of the group consisting of said upper sleeve and said lower sleeve. A9. The rigidizer of claim Al, further comprising: a radial spacer disposed between said first leg and one of the group consisting of said upper sleeve and said lower sleeve. B1. A rigidizer for strengthening a tubular string comprising: upper and lower sleeves each having first and second semi-circular pivotally connected portions, each of said first and second semi-circular pivotally connected portions characterized by having an open configuration and a closed configuration, said upper and lower sleeves being dimensioned to clamp about said tubular string when in said closed configuration; and a plurality of telescopic legs radially disposed about said upper and lower sleeves and rigidly connected between said upper and lower sleeves so as to hold said upper and lower sleeves in coaxial alignment separated by a first axial distance; whereby said rigidizer is operable to removably clamp about and thereby strengthen said string. B2. The rigidizer of claim B1, wherein: said plurality of telescopic legs include, first, second, third, and fourth telescopic legs, each having an elongated inner tubular member slideably disposed within an elongated outer tubular member. B3. The rigidizer of claim B2 wherein each of said plurality of telescopic legs further comprises: a locking system including a pin removably disposed through apertures formed in said inner and outer tubular members. B4. The rigidizer of claim B1, further comprising: an inner diameter adjustment mechanism coupled to one of the group consisting of said upper sleeve and said lower sleeve. C1. A method for handling a tubular string comprising the steps of: positioning said string in a substantially horizontal orientation; providing a rigidizer including upper and lower sleeves, each upper and lower sleeve having first and second semi-circular pivotally connected portions, each of said first and second semi-circular pivotally connected portions characterized by having an open configuration and a closed configuration, said upper and lower sleeves being dimensioned to clamp about said tubular string when in said closed configuration, said rigidizer further including a first leg rigidly connected between said upper and lower sleeves so as to hold said upper and lower sleeves in coaxial alignment separated by a first axial distance; opening said rigidizer; positioning said opened rigidizer about said string; and closing said rigidizer about said string so as to clamp said rigidizer to said string. C2. The method of claim C1 further comprising the steps of: positioning said string having said rigidizer clamped thereto in a substantially vertical orientation; and then opening said rigidizer; and removing said rigidizer from said string. C3. The method of claim C1 further comprising the steps of: adjusting said rigidizer so that said upper and lower sleeves are separated by a second axial distance by said first leg. C4. The method of claim C3 wherein: said first leg is telescopic, having an elongated inner tubular member slideably disposed within an elongated outer tubular member; and the method further comprises the steps of, selectively positioning said inner tubular member within said outer tubular member, and then locking said inner tubular member with respect to said outer tubular member. C5. The method of claim C4 wherein the step of locking said inner tubular member with respect to said outer tubular member further comprises the step of: disposing a pin through said inner tubular member and said outer tubular member. C6. The method of claim C1 further comprising the step of: latching said rigidizer in said closed orientation. C7. The method of claim C1 further comprising the step of: adjusting an inner diameter of at least one of the group consisting of said upper sleeve and said lower sleeve. 